1. Field of the Invention
The present invention is directed to an implantable medical system, for administering therapy in vivo to living tissue, of the type including an implantable therapy-generating apparatus connected to a treatment site remote from the apparatus, as well as to such a medical system having at least two separate implantable therapy-generating apparatus, with the capability of communicating between the two implanted apparatuses.
2. Description of the Prior Art
Many types of implantable medical devices, such as pacemakers and defibrillators, are employed in systems for connection to living tissue for sensing tissue functions or for treating the tissue. The devices can be implantable or extracorporeal. The devices are connected to the living tissue by metallic conductors. A plurality of such devices can be used in a single system, each device being connected to the living tissue, and the implanted devices being interconnected with metallic conductors so that information can be exchanged between the devices.
Metallic leads can cause problems, particularly in implanted systems. A conductor used to transmit pacemaker pulses between a pacing pulse generator and a treatment site may, for example, pick up a defibrillation pulse generated by another device, thereby resulting in a spurious detection of cardiac activity, and may also damage the pacemaker electronics. The metallic conductors are usually contained in an insulating sheath made of a polymer, such as silicone, to keep the leads from having any effect on the surrounding tissue which is not to be sensed or stimulated. The requirement for such an insulating sheath means that the lead cannot be made as thin as is desirable.